1. Field of the Invention
The present invention relates to light flash recovery. More particularly, the present invention relates to a method and apparatus for using a flash recovery timer and warning device to monitor flash recovery.
2. General Background of the Invention
Ordinary work and household illumination levels provide little challenge to the vision tissue of the healthy eye to maintain continuous vision. Brighter light exposure such as looking at fluorescent tubes or bright flashes such as camera flashes can temporarily "flash-blind" or "snow-blind" the central retina. In healthy eyes, the central vision recovers within a few seconds from a single brief bright light exposure.
In the presence of eye diseases that produce either edematous swelling of the central retina or deterioration of some of the tissues in the central retina, the amount of time required to recover from such brief bright light exposure is prolonged, in some cases greatly prolonged. Examples of eye diseases that can produce prolonged flash recovery times include diabetes related retina disease (diabetic cystoid macular edema) and macular degeneration with macular edema and other changes. These diseases affect millions of Americans.
In the early stages of certain eye diseases, flash recovery times may not be prolonged. With changes or worsening of the disease such as the new appearance of tissue swelling or the appearance of a bad blood vessel with leakage or bleeding, the flash recovery time can be greatly prolonged. The early detection of disease appearing or worsening, which can be warned of by prolongation of flash recovery time, could assist patients in obtaining professional help earlier.
The following patents are incorporated herein by reference: U.S. Pat. Nos. 4,545,658; 5,080,478; 5,065,767; 4,764,007; 2,247,653; 3,684,355; 2,232,316; and 2,283,769.
U.S. Pat. No. 4,545,658 discloses a portable flash device designed to temporarily "blind" the eye, and record the time of recovery to normal.
U.S. Pat. No. 2,283,769 discloses eye testing by placing a bright light in the eyes and temporarily "blinding" the person, then measuring the recovery time.
U.S. Pat. Nos. 2,247,653, 5,080,478, 4,764,007 and 3,684,355 disclose devices for testing glare and darkness on the eyes and measuring recovery.